A computational method tailored for the simulation of fluidic thrust-vectoring systems is employed to investigate the dynamic response of a dual-throat nozzle in open-and closed-loop control. Thrust vectoring in fixed, symmetric nozzles is obtained by secondary flow injections that cause local flow separations, asymmetric pressure distributions, and, as a consequence, the vectoring of primary jet flow. The computational technique is based on a well-assessed mathematical model for the compressible unsteady Reynolds-averaged Navier-Stokes equations. A minimal control system governs the unsteady blowing. Nozzle performances and thrust-vector angles have been computed for a wide range of nozzle pressure ratios and secondary flow injection rates. The numerical results are compared with the experimental data available in the open literature. Several computations of the open-loop dynamics of the nozzle under different forcing have been performed to investigate the system response in terms of thrust-vectoring effectiveness and controllability. These computations have been used to extract autoregressive exogenous models of the nozzle dynamics. The effects of including the actuator dynamics are also discussed. Simple strategies of closed-loop control of the nozzle system by proportional-integrative-derivative regulators are investigated numerically. The closed-loop model predictive control of the system, based on the autoregressive exogenous models, is addressed.

The paper focuses on the integration of a non-linear one-dimensional model of Synthetic Jet (SJ) actuator in a well-assessed numerical simulation method for turbulent compressible flows. The computational approach is intended to the implementation of a numerical tool suited for flow control simulations with affordable CPU resources. A strong compromise is sought between the use of boundary conditions or zero-dimensional models and the full simulation of the actuator cavity, in view of long-term simulation with multiple synthetic jet actuators. The model is integrated in a multi-domain numerical procedure where the controlled flow field is simulated by a standard CFD method for compressible RANS equations, while flow inside the actuator is reduced to a one-dimensional duct flow with a moving piston. The non-linear matching between the two systems, which ensures conservation of the mass, momentum and energy is explained. The numerical method is successfully tested against three typical test cases: the jet in quiescent air, the SJ in cross flow and the flow control on the NACA0015 airfoil.

The paper focuses on a computational method for the investigation of Fluidic Thrust Vectoring (FTV). Thrust vectoring in symmetric nozzles is obtained by secondary flow injections that cause local flow separations, asymmetric pressure distributions and, therefore, the vectoring of the primary jet thrust. The methodology proposed here can be applied for studying numerically most of the strategies for fluidic thrust vectoring, as shock-vector control, sonic-plane skewing and the counterflow method. The computational technique is based on a well-assessed mathematical model. The flow governing equations are solved according to a finite volume discretization technique of the compressible RANS equations coupled with the Spalart-Allmaras turbulence model. Second order accuracy in space and time is achieved using an Essentially Non Oscillatory scheme. For validation purposes, the proposed numerical tool is used for the simulation of thrust vectoring based on the dual-throat nozzle concept. Nozzle performances and thrust vector angles are computed for a wide range of nozzle pressure ratios and secondary flow injection rates. The numerical results obtained are compared with the experimental data available in the open literature.